Thermoplastic resin composition and molded product thereof

ABSTRACT

Thermoplastic resin composition providing improved molding efficiency due to high flowability and a high crystallization temperature, while ensuring desired physical properties (e.g., strength) in a molded product. Also, molded product of the composition. The thermoplastic resin composition comprises a plurality of thermoplastic resins having a melt viscosity different from each other and containing a unit which comprises an arylene group and an ether group and/or a carbonyl group. The thermoplastic resin composition may comprise a first thermoplastic resin having a melt viscosity of 150 to 1500 Pa·s at a temperature of 400° C. and a shear rate of 1216 s −1  and a second thermoplastic resin, wherein the melt viscosity ratio of the first thermoplastic resin relative to the second thermoplastic resin, at a temperature of 400° C. and a shear rate of 1216 s −1 , is 1.5:1 to 10:1.

CROSS REFERENCE WITH PCT APP

The present application is a 37 C.F.R. §1.53(b) divisional of, andclaims priority to, U.S. application Ser. No. 13/380,650, filed Dec. 23,2011, now U.S. Pat. No. 8,663,542. Application Ser. No. 13/380,650 isthe national phase under 35 U.S.C. §371 of International Application No.PCT/JP2010/061697, filed on Jul. 9, 2010. Priority is also claimed toJapanese Application No. 2009-162660 filed on Jul. 9, 2009. The entirecontents of each of these applications is hereby incorporated byreference.

TECHNICAL FIELD

The present invention relates to a thermoplastic resin composition (forexample, a polyetherketone resin composition) of which the moldingefficiency can be improved while ensuring a desired physical properties(e.g., mechanical strength) in a molded product, and a molded product ofthe resin composition.

BACKGROUND ART

A polyetherketone resin [such as a polyetheretherketone (PEEK) or apolyetherketone (PEK)] is a typical semicrystalline thermoplastic resinhaving excellent heat resistance, chemical resistance, mechanicalstrength, and others. The polyetherketone resin was developed by ICI in1978, since then the resin has been used for various application fields,with which the conventional synthetic resins could not cope.

As one of characteristics of PEEK and PEK, which are different from theconventional thermoplastic resins, a higher-order structure thereof isexemplified. A common semicrystalline thermoplastic resin usually has acrystalline phase and an amorphous phase in a solidified state thereof.On the other hand, a polymer compound having a benzene ring or anaphthalene ring in a main chain thereof (e.g., a PEEK and a PEK) has alow-motile amorphous phase called a rigid amorphous, in addition to thecrystalline phase and the amorphous phase, which was, for example,reported by a research team of Tokyo Institute of Technology in Societyof Polymer Science, Japan, Annual Meeting, in 1999 [Nonpatent Document 1(Polymer Preprints, Japan, vol. 48, No. 14, p. 3735, 1999)]. Due to sucha complex higher-order structure, the polymer compound usually has alarge dependency on the molecular weight and the molecular weightdistribution of physical properties (particularly, the melt viscosity orthe crystallization rate) compared with the common semicrystallinepolymer. Furthermore, such a large dependency has great effects onmechanical properties of the product after molding process, which areinfluenced by the melt viscosity or the crystallization rate. On theother hand, the polymerization process for the PEEK or the PEK is verycomplicated compared with the conventional common synthetic resins inthe following respects: the particularity of a solvent to be used, thehigh polymerization temperature or high viscosity derived from a highmelting point (Tm) or glass transition temperature (Tg) of a synthesizedpolymer, the necessity of a step for washing a solvent or a remainingmonomer in a final process of polymerization, and others. Thus, forexample, it is not necessarily easy to develop various grades ofpolyetherketone resins with different molecular weights by controllingthe polymerization reaction, differently from a polyamide resin or apolyester resin. Further, it is more difficult to control the molecularweight distribution, and a grade having a suitable moldability accordingto application has not been necessarily provided in the market.

Thus, the higher-order structure (e.g., crystal structure) of thepolyetherketone resin is complicated. Compared with a commonthermoplastic resin, it is difficult to precisely adjust thehigher-order structure of the polyetherketone resin by thepolymerization condition, due to a low solubility or a high meltviscosity thereof. Moreover, when the higher-order structure cannot beadjusted precisely, it is difficult to stably obtain a polyetherketoneresin having a desired melt viscosity or crystallization temperature,and others. In order to stably obtain a molded product having desiredmechanical properties from such a polyetherketone resin, enoughconsideration is needed for a molding process thereof. In particular,the melt viscosity or the crystallization temperature has effects on notonly the strength of the molded product but also the working efficiencyin a molding process thereof. Therefore, a large technical problem ishow to adjust the melt viscosity or the crystallization temperature.

The method for obtaining a resin composition having desired physicalproperties includes, for example, a method which comprises adding two ormore resins suitably. Japanese Patent Application Laid-Open No.2006-241201 (Patent Document 1, JP-2006-241201A) discloses astyrene-series resin composition comprising (A) one of morestyrene-series resins and (B) a thermoplastic resin other than astyrene-series resin, and having a bi-phase continuous structure havinga structural period of 0.001 to 1 μm or a dispersed structure having aintergranular distance of 0.001 to 1 μm, wherein the melt viscosityratio of these components at 180 to 300° C. and a shear rate of 1000 s⁻¹[the component (A)/the component (B)] is not less than 0.1. However, thestyrene-series resin is not a crystalline thermoplastic resin and cannotimprove the molding cycle even by mixing two kinds of resins.

Japanese Patent Application Laid-Open No. 2008-528768 (Patent Document2, JP-2008-528768A) discloses a method of manufacturing an electricallyconductive composition comprising forming a reduced viscosity moltenmasterbatch by mixing a molten masterbatch with a first polymer, whereinthe first polymer has a melt viscosity that is lower than the meltviscosity of the molten masterbatch; and mixing the reduced viscositymasterbatch with a second polymer. However, the molten masterbatch ismixed with the first polymer having a different melt viscosity in orderto improve the compatibility with the second polymer, and the mixture ismixed with the second polymer. Thus, such a mixing has a small effect onthe molding cycle and the mechanical properties of a molded productthereof.

Japanese Patent Application Laid-Open No. 2007-506833 (Patent Document3, JP-2007-506833A) discloses that a pack comprising a polymericmaterial having a melt viscosity (MV) in the range 0.05 to 0.12 kNsm⁻²wherein said polymeric material is of a type which includes: (a) phenylmoieties, (b) carbonyl moieties, and (c) ether moieties. This documentalso discloses a mixture containing a plurality of low-viscositypolyetheretherketones. However, since the low-viscositypolyetheretherketones are mixed together to obtain a highly packingmaterial, the molding cycle or the mechanical properties of a moldedproduct thereof cannot be improved.

WO2009/057255 publication (Patent Document 4) discloses apolyetheretherketone comprising (A) a polymerization component having amolecular weight of not lower than 5,000 and lower than 2,000,000 and(B) a polymerization component having a molecular weight of not lowerthan 1,000 and lower than 5,000, wherein the weight ratio of (A):(B) is60:40 to 97:3. However, since the polyetheretherketone contains theoligomer component (B) in addition to the resin component (A), themechanical properties are deteriorated while improving the flowability.

RELATED ART DOCUMENTS Patent Documents

-   Patent Document 1: JP-2006-241201A (Claims)-   Patent Document 2: JP-2008-528768A (Claims)-   Patent Document 3: JP-2007-506833A (Claims)-   Patent Document 4: WO2009/057255 (Claims)

Nonpatent Documents

-   Nonpatent Document 1: Polymer Preprints, Japan, vol. 48, No. 14, p.    3735, 1999

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

It is an object of the present invention to provide a thermoplasticresin composition (e.g., a polyetherketone resin composition) of whichthe molding efficiency can be improved due to a high flowability thereofwhile ensuring physical properties (such as a strength) in a moldedproduct, and a molded product of the composition.

Another object of the present invention is to provide a thermoplasticresin composition (e.g., a polyetherketone resin composition) of whichthe molding cycle can be improved due to an improved crystallizationtemperature thereof, and a molded product of the composition.

It is still another object of the present invention provide athermoplastic resin composition (e.g., a polyetherketone resincomposition) of which the dimensional stability of the molded productcan be improved, and a molded product of the composition.

Means to Solve the Problems

The inventor of the present invention made intensive studies to achievethe above objects and finally found that the resin properties can besignificantly improved by mixing a plurality of specific thermoplasticresins having a melt viscosity different from each other without specialpolymerization conditions or molding conditions, for example, (1) when,to a hardly injection-moldable first thermoplastic resin having a highmelt viscosity and a low flowability, a small amount of a secondthermoplastic resin having a minimum molecular weight required to securethe properties of a molded product thereof is added, the resulting resincomposition has an increased crystallization temperature and an improvedthe molding cycle, and (2) when a small amount of the firstthermoplastic resin is added to the second thermoplastic resin, theresulting resin composition has significantly improved physicalproperties such as mechanical properties. The present invention wasaccomplished based on the above findings.

That is, the thermoplastic resin composition of the present inventioncomprises a plurality of thermoplastic resins having a melt viscositydifferent from each other; the thermoplastic resins each contain a unitwhich comprises an arylene group and a carbonyl group and/or an ethergroup. The thermoplastic resin at least comprises a first thermoplasticresin and a second thermoplastic resin, and the first thermoplasticresin has a melt viscosity of about 150 to 1500 Pa·s at a temperature of400° C. and a shear rate of 1216 s⁻¹. The melt viscosity ratio of thefirst thermoplastic resin relative to the second thermoplastic resin ata temperature of 400° C. and a shear rate of 1216 s⁻¹ is about 1.5/1 to10/1 (for example, about 3/1 to 5/1) as a ratio of the former/thelatter.

The thermoplastic resins may comprise a polyetherketone resin (forexample, at least one member selected from the group consisting of apolyetheretherketone and a polyetherketone).

The melt viscosity of the second thermoplastic resin at the temperatureof 400° C. and the shear rate of 1216 s⁻¹ may be about 90 to 150 Pa·s.

The ratio (weight ratio) of the first thermoplastic resin relative tothe second thermoplastic resin is not particularly limited to a specificone, and may be selected from the range of about 99/1 to 1/99 as a ratioof the former/the latter. For example, when the ratio of the secondthermoplastic resin relative to 100 parts by weight of the firstthermoplastic resin is small (about 1 to 50 parts by weight, e.g., about1 to 45 parts by weight), the crystallization temperature of the resincomposition (the first thermoplastic resin) can be significantlyimproved. On the other hand, when the ratio of the first thermoplasticresin relative to 100 parts by weight of the second thermoplastic resinis small (about 1 to 50 parts by weight, e.g., about 1 to 45 parts byweight), the physical properties (e.g., mechanical properties) of theresin composition (the second thermoplastic resin) can significantly beimproved. The crystallization temperature of the thermoplastic resincomposition of the present invention may be higher than the weightedaverage of the crystallization temperatures of the plurality of thethermoplastic resins, and, for example, may be not lower than thecrystallization temperature of the second thermoplastic resin.

The thermoplastic resin composition may be obtained by melt-kneading theplurality of thermoplastic resins. Moreover, the thermoplastic resincomposition may have one or a plurality of molecular weight peaks in amolecular weight measurement by a gel filtration chromatography. Thepresent invention also includes a method for increasing acrystallization temperature of a thermoplastic resin composition (afirst thermoplastic resin), which comprises adding, to a firstthermoplastic resin having a melt viscosity of about 150 to 1500 Pa·s ata temperature of 400° C. and a shear rate of 1216 s⁻¹, a secondthermoplastic resin, wherein the melt viscosity ratio of the firstthermoplastic resin relative to the second thermoplastic resin at atemperature of 400° C. and a shear rate of 1216 s⁻¹ about 1.5/1 to 10/1as a ratio of the former/the latter. According to the method, acrystallization temperature of the resin composition can be higher thanthat of the weighted average of the first thermoplastic resin and thesecond thermoplastic resin.

Moreover, the present invention includes a molded product formed fromthe thermoplastic resin composition. The molded product may be formed byinjection molding. The molded product of the present invention may be amolded product which has a thin molded portion, for example, a regionhaving a thickness of not more than 2 mm, or a molded product which hasa region (e.g., a band-like region) having a thickness of not more than2 mm and a width of not more than 10 mm.

Effects of the Invention

According to the present invention, since a plurality of specificthermoplastic resins having a melt viscosity different from each otherare mixed together without special polymerization conditions or moldingconditions, the flowability and the crystallization temperature of theresin composition can be increased and the molding efficiency thereofcan be significantly improved while ensuring the mechanical propertiesof the molded product. In particular, the larger the difference in meltviscosity is, the larger the improvement effect of the moldingefficiency is. More specifically, addition, to a hardlyinjection-moldable first thermoplastic resin having a high meltviscosity and a low flowability, of a small amount of a secondthermoplastic resin having a minimum molecular weight required to securethe properties of a molded product thereof can significantly increasethe crystallization temperature. On the other hand, addition of a smallamount of the first thermoplastic resin to the second thermoplasticresin can significantly improve the mechanical properties of the moldedproduct. The thermoplastic resin composition of the present inventioncan have a crystallization temperature higher than that expected fromthe crystallization temperatures of the thermoplastic resins to be mixed(the weighted average crystallization temperature) and can becrystallized in a short time and released from a metal mold. Therefore,the molding cycle can drastically be shortened. Moreover, according tothe present invention, due to a high crystallization temperature and alarge crystallization rate, the dimensional stability of the moldedproduct can also be improved.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a graph showing crystallization temperatures ofpolyetherketone resins or compositions in Examples and ComparativeExamples.

DESCRIPTION OF EMBODIMENTS

The thermoplastic resin composition of the present invention contains aplurality of (e.g., about 2 to 4, preferably about 2 to 3) thermoplasticresins (e.g., crystalline thermoplastic resins) having a melt viscositydifferent from each other. Each one of the thermoplastic resins containsa unit comprising an arylene group and an ether group and/or a carbonylgroup, for example, a unit represented by the following formula (1):

[wherein, the ring Z represents an arene ring, and R is the same ordifferent from each other in each unit and represents an oxygen atom ora carbonyl group (—C(O)—).] In each unit, the species of the group R andthe ring Z may be the same or different from each other. Incidentally,the group R may be a —C(O)O— bond (ester bond) in some units. Usually,the group R is not a —C(O)O— bond.

The arene ring represented by the ring Z may include a C₆₋₁₀arene ringsuch as benzene or naphthalene, a C₆₋₁₀aryl C₆₋₁₀arene ring such asbiphenyl or binaphthyl, and others. Incidentally, the ring Z may have asubstituent. The substituent may include a C₁₋₆alkyl group such asmethyl or ethyl group (preferably a C₁₋₄alkyl group), and others.

The thermoplastic resin may for example be a polyphenyleneether-seriesresin (e.g., a polyphenyleneether and a modified polyphenyleneether),and usually a polyetherketone resin (an aromatic polyetherketone resin).The polyetherketone resin is not particularly limited to a specific oneand, usually, the resin suitably contains an arylene group (e.g.,phenylene group), a carbonyl group, and an ether group. For example, thepolyetherketone resin may include a polyetherketone, apolyetheretherketone, a polyetherketoneketone, apolyetherketoneetherketoneketone, a polyetheretherketoneketone, and apolyether-diphenyl-ether-phenyl-ketone-phenyl.

These thermoplastic resins may be used alone or in combination. Amongthese thermoplastic resins, a polyetherketone resin is preferred, and apolyetheretherketone or a polyetherketone is particularly preferred.

The combination of the thermoplastic resins in the thermoplastic resincomposition is not particularly limited to a specific one. Thecombination of the polyetherketone resins of the same kind (e.g., acombination of a plurality of polyetheretherketones only, and acombination of a plurality of polyetherketones only) is preferred.

The molecular weight of the thermoplastic resin is not particularlylimited to a specific one as far as the thermoplastic resin can bemelt-kneaded or molded. For example, the number average molecular weightof the thermoplastic resin may be not less than 5,000 (e.g., about 5,000to 1,000,000), preferably not less than 8,000 (e.g., about 10,000 to500,000), more preferably not less than 15,000 (e.g., about 18,000 to100,000), and particularly not less than 20,000 (e.g., about 20,000 to50,000) in terms of polystyrene in a gel permeation chromatography(GPC). Moreover, the molecular weight distribution (Mw/Mn) may forexample be about 1.5 to 5, preferably about 1.8 to 4, and morepreferably about 2 to 3.5. Incidentally, for the thermoplastic resin, asthe molecular weight is higher, usually the mechanical properties of theresin are improved and the flowability decreases. However, thepolyetherketone resin shows a specific behavior due to a smallentanglement molecular weight. That is, only slight increase of themolecular weight significantly changes (e.g., lowers) the flowability.Moreover, when the molecular weight is increased, the entangling of themolecules is increased and the crystallization rate is lowered.Therefore, the physical properties (e.g., mechanical properties)complicatedly vary depending on the molecular weight.

The melt viscosity of the thermoplastic resin is not particularlylimited to a specific one. For example, the melt viscosity of thethermoplastic resin at a temperature of 400° C. and a shear rate of 1216s⁻¹ may be selected from the range of about 90 to 1500 Pa·s, and may beabout 90 to 800 Pa·s, preferably about 95 to 700 Pa·s, and morepreferably about 100 to 600 Pa·s (e.g., about 100 to 500 Pa·s).Incidentally, a resin having a melt viscosity of lower than 90 Pa·s hasa molecular weight in an oligomer region. Even when such a resin ismixed with a high-viscosity thermoplastic resin, the resulting mixturesometimes fails to improve the mechanical strength of the molded productthereof.

The crystallization temperature of the thermoplastic resin is notparticularly limited to a specific one as far as the thermoplastic resincan be melt-kneaded or molded. For example, the crystallizationtemperature of the thermoplastic resin at a cooling rate of 5° C./minutemay be about 290 to 310° C., preferably about 291 to 309° C., and morepreferably about 292 to 308° C.

These thermoplastic resins to be used may be products on the market ormay be produced by a known method. For example, a representativeproduction process of the polyetherketone resin may include a processwhich comprises polycondensing an aromatic diol component and anaromatic dihalide component (provided that any one of these componentscontains a component having at least a carbonyl group), or aromaticmonohalide monool components (provided that any one of the componentscontains an aromatic monohalide monool component having at least acarbonyl group) at a temperature range of 150° C. to 400° C. in thepresence of an alkali metal salt and a solvent.

Examples of the aromatic diol component may include hydroquinone,examples of the aromatic dihalide component may include4,4′-difluorobenzophenone, and examples of the aromatic monohalidemonool component may include 4-fluorophenol and4-fluoro-4′-hydroxybenzophenone.

The alkali metal salt may include, for example, anhydrous potassiumcarbonate. Examples of the solvent may include diphenylsulfone.

After the polycondensation reaction is completed, the resulting resinmay be pulverized, washed with acetone, methanol, ethanol, water, or thelike, and dried. Incidentally, the crystallization temperature of thepolyetherketone resin may suitably be adjusted by modifying a terminalgroup thereof (usually, a halogen atom) with an alkaline sulfonic acidgroup (e.g., sodium sulfonate group, potassium sulfonate group, andlithium sulfonate group). It is preferable that the resin be usedwithout modifying a terminal group thereof.

The thermoplastic resin composition at least comprises a firstthermoplastic resin (e.g., a higher-viscosity thermoplastic resin) and asecond thermoplastic resin (e.g., a lower-viscosity thermoplastic resin)having a melt viscosity different from each other. The chemicalstructure of the first thermoplastic resin and that of the secondthermoplastic resin may be the same or different from each other. Evenwhen these resins have the same chemical structure, the resin propertiescan significantly be improved.

Among the plurality of thermoplastic resins contained in thethermoplastic resin composition, the melt viscosity of the firstthermoplastic resin (e.g., a thermoplastic resin having the highest meltviscosity) at a temperature of 400° C. and a shear rate of 1216 s⁻¹ mayfor example be selected from the range of not less than 150 Pa·s (e.g.,about 150 to 1500 Pa·s) and may for example be not less than 160 Pa·s(e.g., about 170 to 800 Pa·s), preferably not less than 200 Pa·s (e.g.,about 250 to 700 Pa·s), more preferably not less than 300 Pa·s (e.g.,about 350 to 600 Pa·s), and particularly not less than 400 Pa·s (e.g.,about 400 to 500 Pa·s). Moreover, the melt viscosity of the secondthermoplastic resin (e.g., a thermoplastic resin having the lowest meltviscosity) at a temperature of 400° C. and a shear rate of 1216 s mayfor example be not more than 170 Pa·s (e.g., about 90 to 160 Pa·s),preferably not more than 150 Pa·s (e.g., about 95 to 140 Pa·s), morepreferably not more than 130 Pa·s (e.g., about 100 to 120 Pa·s), andparticularly not more than 110 Pa·s (e.g., about 100 to 110 Pa·s). Whenthe melt viscosity of the second thermoplastic resin is higher than 170Pa·s, it is sometimes difficult to obtain a desired flowability.

In view of a significant improvement of resin properties, at atemperature of 400° C. and a shear rate of 1216 s⁻¹, the melt viscosityratio of the first thermoplastic resin relative to the secondthermoplastic resin [the former/the latter] may be about 1.5/1 to 10/1,preferably about 2/1 to 8/1 (e.g., about 2.5/1 to 6/1), and morepreferably about 3/1 to 5/1. When the melt viscosity of the firstthermoplastic resin is lower than 1.5 times of that of the secondthermoplastic resin, there is a tendency that properties of resinscontained in the composition are too similar. Therefore, it is sometimesdifficult to obtain a desired crystallinity, mechanical strength, andothers.

According to the present invention, only addition of a small amount ofone of the first thermoplastic resin and the second thermoplastic resinto the other thermoplastic resin allows the characteristics (e.g.,crystallization temperature, and mechanical properties such as impactresistance) of the composition to be improved significantly. Thus, theweight ratio of the first thermoplastic resin relative to the secondthermoplastic resin is not particularly limited to a specific one, andmay suitably be selected from the range of about 99/1 to 1/99 as a ratioof the former/the latter. For example, when the strength of the moldedproduct to be obtained is regarded as important, the first thermoplasticresin/the second thermoplastic resin (weight ratio) may be about 95/5 to50/50, preferably about 90/10 to 60/40 (e.g., about 85/15 to 65/35), andmore preferably about 80/20 to 70/30. When the moldability is regardedas important, the first thermoplastic resin/the second thermoplasticresin (weight ratio) may be about 50/50 to 1/99 (e.g., about 45/55 to5/95), preferably about 40/60 to 10/90 (e.g., about 35/65 to 10/90), andmore preferably about 30/70 to 10/90.

In particular, when the second thermoplastic resin relative to 100 partsby weight of the first thermoplastic resin is about 1 to 50 parts byweight (e.g., about 1 to 45 parts by weight, preferably about 10 to 40parts by weight, and preferably about 20 to 35 parts by weight), theresulting resin composition can improve the crystallization temperatureand drastically shorten the molding cycle. On the other hand, when thefirst thermoplastic resin relative to 100 parts by weight of the secondthermoplastic resin is about 1 to 50 parts by weight (e.g., about 1 to45 parts by weight, preferably about 10 to 40 parts by weight, andpreferably about 20 to 35 parts by weight), the resulting resincomposition can significantly improve the physical properties (such asmechanical properties).

The proportion of the total of the first thermoplastic resin and thesecond thermoplastic resin in the whole thermoplastic resin compositionmay for example be not less than 50% by weight, preferably not less than70% by weight, more preferably not less than 80% by weight (e.g., about90 to 100% by weight).

The melt viscosity of the thermoplastic resin composition at atemperature of 400° C. and a shear rate of 1216 s⁻¹ is about 100 to 800Pa·s (e.g., about 100 to 700 Pa·s), preferably about 100 to 600 Pa·s,and more preferably about 110 to 500 Pa·s (e.g., about 120 to 450 Pa·sand preferably about 130 to 400 Pa·s). When the melt viscosity is lowerthan 100 Pa·s, there is sometimes a problem on the strength of theobtained molded product. When the melt viscosity is higher than 800Pa·s, there is sometimes a problem on the moldability.

The thermoplastic resin composition of the present invention has a highcrystallization temperature. The crystallization temperature is anindicator which reflects a crystallization rate affecting a time cycleof a molding step. That is, the crystallization rate can be evaluated bya crystallization temperature on cooling a molten substance at aconstant cooling rate, for example, in a differential scanningcalorimetry. The higher the crystallization temperature is, the largerthe crystallization rate is, and the molding cycle can be shortened. Thecrystallization temperature of the thermoplastic resin composition mayfor example be not lower than 300° C., preferably not lower than 303°C., and more preferably not lower than 306° C. (e.g., about 306 to 308°C.). When the crystallization temperature is lower than 300° C., ittakes a time to release the composition from a metal mold after moldingstep, which has sometimes an adverse effect on the molding cycle.

The crystallization temperature of the thermoplastic resin compositionmay for example be not lower than the crystallization temperature of thefirst thermoplastic resin (for example, not lower than the lowestcrystallization temperature among the crystallization temperatures ofthe resins constituting the composition), preferably higher than theweighted average of the crystallization temperatures of the constituentresins, more preferably not lower than the crystallization temperatureof the second thermoplastic resin (for example, not lower than thehighest crystallization temperature among the crystallizationtemperatures of the constituent resins), and not higher than theweighted average crystallization temperature plus 1 to 10° C. (e.g., 1to 5° C.). Since such a thermoplastic resin composition is crystallizedat a higher temperature compared with the case where any one, some, orall of resins constituting the composition are used independently (orseparately), the composition can achieve an improvement in theshortening of the molding cycle, such as rapid release from a metal molddue to a faster crystallization, for example, after from a melt-kneadingstep through a molding step (such as extrusion or injection).Incidentally, the crystallization temperatures of each thermoplasticresin and resin composition mean a crystallization temperature in aprocess composed of heating from −10° C. to 410° C. at a rate of 20°C./minute, maintaining at 410° C. for one minute, cooling at a coolingrate of 5° C./minute. The crystallization temperatures can be measuredby a differential scanning calorimeter.

The thermoplastic resin composition also has well-balanced flowabilityand mechanical properties. For example, the flow length (spiral flow)under the conditions of a width of 6 mm, a thickness of 2 mm, a cylindertemperature of 380° C., a metal mold temperature of 180° C., and apressure of 1000 bar may be about 30 to 70 cm, preferably about 35 to 65cm, and more preferably about 40 to 60 cm (e.g., about 45 to 55 cm).Moreover, the tensile strength at break is about 95 to 120 MPa andpreferably about 100 to 110 MPa in accordance with ISO527. Moreover, theCharpy impact strength may be about 8 to 20 KJ/m², preferably about 9 to18 KJ/m², and more preferably about 10 to 15 KJ/m² in accordance withISO179/1eA. Incidentally, when there is a large difference between thethermoplastic resins to be mixed in melt viscosity, the impact strengthof the resin composition can be further improved. For example, theimpact strength of the resin composition can be larger than the impactstrength (that) of the thermoplastic resin alone.

The thermoplastic resin composition may have a single peak or may havetwo or more molecular weight peaks in a molecular weight by a gelfiltration chromatography. Moreover, the molecular weight peaks maycorrespond to each thermoplastic resin. The presence of the differentmolecular weight peaks improves the crystal structure or the packingstructure in a molecule level thereof after melt-kneading, and thensignificantly improves the strength of the resin composition.Specifically, it is presumed that a resin having a low molecular weightfunctions as a kind of nucleation agent. In particular, when thephysical properties (e.g., melt viscosity, crystallization temperature,and crystallization rate) of a resin having low molecular weight aregreatly different from those of a resin having a high molecular weight,these physical properties of the obtained resin composition can beimproved markedly. The composition may be obtained by mixing two or moreresins with different molecular weights or obtained under such aproduction process conditions as a polymerization process conditions toobtain one or more molecular weight peaks. Thus, the thermoplastic resincomposition of the present invention can greatly improve thecrystallization temperature without containing a nucleation agentsubstantially.

Incidentally, although the number of molecular weight peaks usuallydepends on the number of resins constituting the composition, is notlimited to the number of the resins (the dependence is not exclusive).One of resins constituting the composition may have two or moremolecular weight peaks, or the composition may comprise two or moreresins each having a molecular weight peak at (in) the same molecularweight value. In order to easily adjust a desired crystallinity ormechanical strength, and others, it is preferable that the resinscontained in the composition have different molecular weights from eachother. The measurement method of a molecular weight in a gel filtrationchromatography is not particularly limited to a specific one, and mayinclude, for example, a method described in Japanese Patent ApplicationLaid-Open No. 2004-45166.

The thermoplastic resin composition may be a mixture of thermoplasticresins constituting the resin composition [or a simple mixture (e.g., adry blend product and a pre-mixture), for example, a pellet mixture, aparticulate (or powder) mixture, or (and) a mixture of pellet andparticulate (or powder)] or may be obtained by melt-kneading a pluralityof thermoplastic resins (or the mixture) constituting the resincomposition. The melt-kneading allows the crystal structure or packingstructure of the resin composition to be improved in a molecule level,which significantly improves the physical properties of the resincomposition and can provide the resin composition having a uniform andstable quality.

The resins constituting the thermoplastic resin composition or thecomposition may contain an additive. The additive may include areinforcer [for example, a particulate reinforcer such as a mineralparticle (e.g., a talc, a silica, and a kaolin), a metal oxide (e.g.,magnesium oxide, aluminum oxide, and zinc oxide), or a metal sulfate(e.g., calcium sulfate and barium sulfate); and a fibrous reinforcersuch as a carbon fiber, a glass fiber, a stainless-steel fiber, or anaramid fiber], a thermal-conductivity improver (e.g., alumina), a colormaterial or a coloring agent (e.g., a carbon black), a stabilizer, aplasticizer, a lubricant, and others. These additives may be used aloneor in combination.

The thermoplastic resin composition can be prepared by a conventionalmanner, for example, by mixing each component. The thermoplastic resincomposition may be prepared, for example, by a dry blend which comprisessimply mixing each component in a particulate or pellet form withoutmelt-kneading [usually, a dry blend which comprises mixing eachcomponent at a room temperature with a mixer (such as a tumbler or aV-shaped blender)] or by melt-kneading each component. Morespecifically, the thermoplastic resin composition is often prepared bypre-mixing each component with a mixer (e.g., a tumbler, a V-shapedblender, a Henschel mixer, a nauta mixer, a ribbon mixer, amechanochemical apparatus, and an extrusion blender) if necessary, andthen melt-kneading each component (or the pre-mixture) at a temperatureof about 300 to 450° C. (preferably about 350 to 400° C.) with a varietyof melt-kneaders (e.g., a kneader, and a monoaxial or biaxial screwextruder). The melt-kneaded product may be pelletized with the use of aconventional pelletizing means (e.g., a pelletizing machine).

The thermoplastic resin composition of the present invention can bemolded (or formed) into a desired shape. The molding method is notparticularly limited to a specific one. The thermoplastic resincomposition can be molded by a known method such as an extrusion moldingor an injection molding. Among these molding methods, an injectionmolding is preferred.

Since the thermoplastic resin composition of the present invention canimprove the crystallization rate due to the improvement of thecrystallization temperature, for example, the difference between thevicinity of the external surface of the molded product and the inside ofthe molded product in crystallinity which usually occurs in a coolingprocess after molding such as an extrusion molding or an injectionmolding can be reduced. As a result, the accuracy of dimension of themolded product can be increased.

The molded product of the present invention is not particularly limitedto a specific one as far as the molded product is formed from thethermoplastic resin composition. The molded product may have a varietyof forms (for example, a two-dimensional form such as a film-like form,a sheet-like form, or a band-like form; and a three-dimensional formsuch as a rod-like form, a pipe-like form, or a solid form). The moldedproduct may be a thin molded product or a molded product having a thinmolded portion, for example, may be a molded product which has a region(a thin region) having a thickness of not more than 2 mm (e.g., about0.01 to 2 mm and preferably about 0.1 to 1.5 mm) or a molded productwhich has a region having a thickness of not more than 2 mm and a widthof not more than 10 mm (e.g., a band-like region or a band-like thinmolded portion). That is, the thermoplastic resin composition of thepresent invention has a high toughness even when subjected tothin-molding. Thus, when the resin composition is molded into a thinfilm-like or sheet-like form or into a thin and narrow band-like form,the resulting molded product has an excellent toughness compared withindividual molded products of the resins constituting the composition.The film-like or sheet-like molded product preferably has a thickness ofnot more than 2 mm (e.g., about 0.01 to 2 mm and preferably about 0.1 to1.5 mm). The band-like molded product preferably has a thickness of notmore than 2 mm (e.g., about 0.01 to 2 mm and preferably about 0.1 to 1.5mm) and a width of 10 mm (e.g., about 1 to 10 mm and preferably about 2to 8 mm).

EXAMPLES

Hereinafter, the following examples are intended to describe thisinvention in further detail and should by no means be interpreted asdefining the scope of the invention.

[Polyetherketone Resin]

The following polyetherketone resins were used.

1000G: Polyetheretherketone VESTAKEEP 1000G (manufactured byDaicel-Evonik Ltd.)

2000G: Polyetheretherketone VESTAKEEP 2000G (manufactured byDaicel-Evonik Ltd.)

4000G: Polyetheretherketone VESTAKEEP 4000G (manufactured byDaicel-Evonik Ltd.)

[Measuring Method of Melt Viscosity]

For each polyetherketone resin or each resin composition, the meltviscosity was measured at 400° C. and a shear rate of 1216 s⁻¹ under aweighting of 0.1 kN on pre-heating using a capillary rheometer(manufactured by Shimadzu Corporation, RHEOLOSTER ACER-01, capillarylength: 10 mm, capillary diameter: 1 mm, and barrel diameter: 9.55 mm).

[Measuring Method of Crystallization Temperature]

Each polyetherketone resin or each resin composition (4.5 to 10.0 mg)was cooled to −10° C. and maintained for one minute, then heated at aheating rate of 20° C./minute and maintained at 410° C. for one minute,and then cooled at a cooling rate of 5° C./minute using a differentialscanning calorimeter (manufactured by Seiko Instruments & ElectronicsLtd., SSC5200). The initially obtained peak position in the coolingprocess was regarded as a crystallization temperature.

[Evaluation of Flowability]

For each polyetherketone resin or each resin composition, the flowlength was measured at a metal mold temperature of 180° C., a cylindertemperature of 380° C., and a pressure of 1000 bar using a metal moldfor spiral flow measurement (width: 6 mm, and thickness: 2 mm).

[Evaluation of Strength at Break]

The strength at break was measured in accordance with ISO527.

[Evaluation of Impact Strength]

The Charpy impact strength was measured in accordance with ISO179/1eA.

[Evaluation of Toughness]

Each polyetherketone resin or each resin composition was formed into aband-like molded product (5 mm in width, 1 mm in thickness, and 500 mmin length). The molded product was bent to form a single loop with adiameter of not less than 20 mm, and both ends of the band were pulledto gradually reduce the diameter of the loop portion. At the time whenthe diameter of the loop was 5 mm, the break status of the loop portionwas observed. Five (5) samples per polyetherketone resin or resincomposition were used to evaluate the toughness. The results wereevaluated based on the following criteria.

A: Not broken (All samples were not broken)

B: Hardly broken (One or two samples were broken)

C: Broken (Three or more samples were broken)

Examples and Comparative Examples

The above-mentioned polyetherketone resins were used alone or mixed in aproportion shown in Table 1. For the resins and the resultingpolyetherketone resin compositions, the melt viscosity, thecrystallization temperature, the flowability, the strength at break, theimpact strength, and the toughness were measured or evaluated. Theresults are shown in Table 1.

TABLE 1 Comparative Examples Examples 1 2 3 1 2 3 4 5 6 7 8 9 1000 G 10090 80 60 40 20 80 60 40 20 (% by weight) 2000 G 100 20 40 60 80 (% byweight) 4000 G 100 10 20 40 60 80 (% by weight) Melt viscosity 104.8164.3 432.0 122.0 144.9 177.2 287.0 343.0 114.8 122.0 134.9 151.4 (Pa ·s) Crystallization 306.0 303.6 295.8 307.1 307.1 307.1 303.1 301.7 305.8305.9 305.7 305.7 temperature (° C.) Flow length (cm) 60 35 27 55 50 4540 35 50 45 35 35 Tensile strength 103 — 96 103 102 101 99 97 — — — — atbreak (MPa) Charpy impact 6 7 8 9 12 9 9 10 8 8 8 8 strength (KJ/m²)Toughness C B A B A A A A B B A A

In all of Examples 2 to 5, it is observed that the resin composition hasan excellent flowability and a high crystallization temperature whilesufficiently maintaining the toughness of resins constituting thecomposition. Among Examples, each of Examples 1 and 2 has notablecharacteristics in the respect that the resin composition has acrystallization temperature higher than the crystallization temperatureof each resin (1000G and 4000G) constituting the composition. Inparticular, Examples 1 and 2, in which a small amount of 4000G was addedto 1000G, have significantly improved mechanical properties (such astoughness and impact strength) compared with the values expected fromthe mixing ratio of 1000G and 4000G. Moreover, Examples 5, in which asmall amount of 1000G was added to 4000G, has a significantly improvedcrystallization temperature compared with the value expected from themixing ratio of 1000G and 4000G [for example, the weighted averagecrystallization temperature (298° C.)].

In all of Examples 6 to 9, it is observed that the resin composition hasa high crystallization temperature while showing a toughness orflowability higher than those of the resins constituting thecomposition. In particular, each of Examples 8 and 9 has notablecharacteristics in the respect that the resin composition has atoughness higher than the toughness of each resin (1000G and 2000G)constituting the composition.

INDUSTRIAL APPLICABILITY

The thermoplastic resin composition of the present invention and themolded product thereof can be used in various forms (such as a film-likeform, a band-like form, a rod-like form, or pipe-like form) as a memberfor a product which needs a heat resistance, a chemical resistance, andtoughness (e.g., a semiconductor, an electronic machine, an automobile,and a flying machine).

The invention claimed is:
 1. A method for improving moldability of athermoplastic resin composition, said composition comprising acombination of a first polyetheretherketone and a secondpolyetheretherketone which have a melt viscosity different from eachother, which comprises adding or mixing the first polyetheretherketonerelative to or with the second polyetheretherketone in a weight ratio ofabout 50/50 to 1/99 as a ratio of the former/the later, andmelt-kneading the resultant mixture, wherein the firstpolyetheretherketone has a melt viscosity of 150 to 1500 Pa·s at atemperature of 400° C. and a shear rate of 1216 s⁻¹, and the meltviscosity ratio of the first polyetheretherketone relative to the secondpolyetheretherketone at a temperature of 400° C. and a shear rate of1216 s⁻¹ is 1.5/1 to 10/1 as a ratio of the former/the latter.
 2. Amethod according to claim 1, wherein the melt viscosity ratio of thefirst polyetheretherketone relative to the second polyetheretherketoneat the temperature of 400° C. and the shear rate of 1216 s⁻¹ is 3/1 to5/1 as a ratio of the former/the latter.
 3. A method according to claim1, wherein the melt viscosity of the second polyetheretherketone at thetemperature of 400° C. and the shear rate of 1216 s⁻¹ is 90 to 150 Pa·s.4. A method according to claim 1, wherein the weight ratio of the firstpolyetheretherketone relative to the second polyetheretherketone isabout 45/55 to 5/95 as a ratio of the former/the later.
 5. A methodaccording to claim 1, wherein the weight ratio of the firstpolyetheretherketone relative to the second polyetheretherketone isabout 40/60 to 10/90 as a ratio of the former/the later.
 6. A methodaccording to claim 1, which increases a crystallization temperature ofthe thermoplastic resin composition.
 7. A method according to claim 1,which increases a crystallization temperature of the thermoplastic resincomposition to a crystallization temperature higher than the weightedaverage of the crystallization temperatures of the first and secondpolyetheretherketones.
 8. A method according to claim 1, which increasesa crystallization temperature of the thermoplastic resin composition toa crystallization temperature of not lower than the crystallizationtemperature of the second polyetheretherketone.
 9. A method according toclaim 1, which increases a crystallization temperature of thethermoplastic resin composition to a crystallization temperature of notlower than the highest crystallization temperature among the first andsecond polyetheretherketones.
 10. A method according to claim 1, whichshortens a molding cycle for improving the moldabiity of thethermoplastic resin composition.
 11. A method for increasing acrystallization temperature of a thermoplastic resin composition orshortening a molding cycle of the thermoplastic resin composition, saidcomposition comprising a combination of a first polyetheretherketone anda second polyetheretherketone which have a melt viscosity different fromeach other, which comprises adding or mixing the firstpolyetheretherketone relative to or with the second polyetheretherketonein a weight ratio of about 50/50 to 1/99 as a ratio of the former/thelater, melt-kneading the resultant mixture, and injecting the moltenmixture into a metal mold, wherein the first polyetheretherketone has amelt viscosity of 150 to 1500 Pa·s at a temperature of 400° C. and ashear rate of 1216 s⁻¹, and the melt viscosity ratio of the firstpolyetheretherketone relative to the second polyetheretherketone at atemperature of 400° C. and a shear rate of 1216 s⁻¹ is 1.5/1 to 10/1 asa ratio of the former/the latter.
 12. A method according to claim 11,wherein a molded product having a region having a thickness of not morethan 2 millimeters is obtained.
 13. A method according to claim 11,wherein a molded product having a region of a thickness of not more than2 millimeters and a width of not more than 10 millimeters is obtained.